The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
John C Chrivia - One of the best experts on this subject based on the ideXlab platform.
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the chromatin remodeling protein SRCAP is critical for deposition of the histone variant h2a z at promoters
Journal of Biological Chemistry, 2007Co-Authors: Madeline M Wong, John C ChriviaAbstract:Abstract Studies in Saccharomyces cerevisiae indicate the histone variant H2A.Z is deposited at promoters by the chromatin remodeling protein Swr1 and plays a critical role in the regulation of transcription. In higher eukaryotes, however, little is known about the distribution, method of deposition, and function of H2A.Z at promoters. Using biochemical studies, we demonstrated previously that SRCAP (SNF-2-related CREB-binding protein activator protein), the human ortholog of Swr1, could catalyze deposition of H2A.Z into nucleosomes. To address whether SRCAP directs H2A.Z deposition in vivo, promoters targeted by SRCAP were identified by a chromatin immunoprecipitation (ChIP)-on-chip assay. ChIP assays on a subset of these promoters confirmed the presence of SRCAP on inactive and active promoters. The highest levels of SRCAP were observed on the active SP-1, G3BP, and FAD synthetase promoters. Detailed analyses of these promoters indicate sites of SRCAP binding overlap or occur adjacent to the sites of H2A.Z deposition. Knockdown of SRCAP levels using siRNA resulted in loss of SRCAP at these promoters, decreased deposition of H2A.Z and acetylated H2A.Z, and a decrease in levels of SP-1, G3BP, and FAD synthetase mRNA. Thus, these studies provide the first evidence that SRCAP is recruited to promoters and is critical for the deposition of H2A.Z.
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the chromatin remodeling protein SRCAP is critical for deposition of the histone variant h2a z at promoters
Journal of Biological Chemistry, 2007Co-Authors: Madeline M Wong, Linda K Cox, John C ChriviaAbstract:Studies in Saccharomyces cerevisiae indicate the histone variant H2A.Z is deposited at promoters by the chromatin remodeling protein Swr1 and plays a critical role in the regulation of transcription. In higher eukaryotes, however, little is known about the distribution, method of deposition, and function of H2A.Z at promoters. Using biochemical studies, we demonstrated previously that SRCAP (SNF-2-related CREB-binding protein activator protein), the human ortholog of Swr1, could catalyze deposition of H2A.Z into nucleosomes. To address whether SRCAP directs H2A.Z deposition in vivo, promoters targeted by SRCAP were identified by a chromatin immunoprecipitation (ChIP)-on-chip assay. ChIP assays on a subset of these promoters confirmed the presence of SRCAP on inactive and active promoters. The highest levels of SRCAP were observed on the active SP-1, G3BP, and FAD synthetase promoters. Detailed analyses of these promoters indicate sites of SRCAP binding overlap or occur adjacent to the sites of H2A.Z deposition. Knockdown of SRCAP levels using siRNA resulted in loss of SRCAP at these promoters, decreased deposition of H2A.Z and acetylated H2A.Z, and a decrease in levels of SP-1, G3BP, and FAD synthetase mRNA. Thus, these studies provide the first evidence that SRCAP is recruited to promoters and is critical for the deposition of H2A.Z.
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purification of a human SRCAP complex that remodels chromatin by incorporating the histone variant h2a z into nucleosomes
Biochemistry, 2006Co-Authors: Donald D Ruhl, Selene K Swanson, Laurence Florens, Michael P Washburn, Ronald C Conaway, Joan Weliky Conaway, John C ChriviaAbstract:The Snf-2-related CREB-binding protein activator protein (SRCAP) serves as a coactivator for a number of transcription factors known to interact with CBP. Swr1, the closest Saccharomyces cerevisiae ortholog of SRCAP, is a component of the chromatin remodeling complex SWR-C, which catalyzes exchange of the histone variant H2A.Z into nucleosomes. In this report, we use a combination of conventional chromatography and anti-SRCAP immunoaffinity chromatography to purify a native human SRCAP complex with a polypeptide composition similar to that of SWR-C, and we show for the first time that this SRCAP-containing complex supports ATP-dependent exchange of histone dimers containing H2B and H2A.Z into mononucleosomes reconstituted with recombinant H2A, H2B, H3, and H4. Our findings, together with previous evidence implicating H2A.Z in transcriptional regulation, suggest that SRCAP's coactivator function may depend on its ability to promote incorporation of H2A.Z into chromatin.
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human SRCAP and drosophila melanogaster dom are homologs that function in the notch signaling pathway
Molecular and Cellular Biology, 2005Co-Authors: Joel C Eissenberg, Madeline Wong, John C ChriviaAbstract:The putative ATPase chromatin-remodeling machine SRCAP was identified in a yeast two-hybrid protein screen by interaction with the histone acetylase CBP. SRCAP is implicated in the transcriptional coactivation of cyclic AMP- and steroid-dependent promoters, but no natural chromosomal targets for SRCAP regulation have been identified. DOM is the unique SRCAP homolog in Drosophila melanogaster. The goal of this study was to test whether SRCAP is a functional homolog of DOM and to identify potential activities and targets of SRCAP in vivo. We show that human SRCAP complements recessive domino mutant phenotypes. This rescue depends on an intact ATPase homology domain. SRCAP colocalizes extensively with DOM on Drosophila polytene chromosomes and is recruited to sites of active transcription, such as steroid-regulated loci, but not to activated heat shock loci. We show that SRCAP recruits Drosophila CBP to ectopic chromosomal sites, providing the first evidence to suggest that SRCAP and CBP interact directly or indirectly on chromosomes. We show that DOM is a Notch pathway activator in Drosophila and that wild-type SRCAP—but not an ATPase domain mutant—can substitute for DOM in Notch-dependent wing development. We show that SRCAP potentiates Notch-dependent gene activation in HeLa cells. Taken together, these data implicate SRCAP and DOM in developmental gene activation.
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snf2 related cbp activator protein SRCAP functions as a coactivator of steroid receptor mediated transcription through synergistic interactions with carm 1 and grip 1
Molecular Endocrinology, 2003Co-Authors: Alexandra M Monroy, Natalie M Schott, Linda K Cox, Don J Chen, Mary F Ruh, John C ChriviaAbstract:SRCAP (SNF2-related CBP activator protein) is a 350-kDa protein that shares homology with the SNF2 family of proteins whose members function in various aspects of transcriptional regulation. In various cell types, SRCAP is found in distinct multiprotein complexes that include proteins found in SWI/SNF chromatin remodeling complexes. SRCAP was identified by its ability to bind to CBP and was found to potentiate the ability of CBP to activate transcription. Studies in our laboratory have demonstrated that SRCAP functions as a coactivator for CREB-mediated transcription of a number of promoters, including that of the phosphoenolpyruvate carboxykinase gene. Our current studies demonstrate that SRCAP enhances phosphoenolpyruvate carboxykinase promoter transcription induced by glucocorticoids. SRCAP also enhances glucocorticoid receptor-mediated transcription of a simple promoter containing only two glucocorticoid response elements, indicating that SRCAP functions as a glucocorticoid receptor coactivator. In similar studies, SRCAP was also found to serve as a coactivator for the androgen receptor. SRCAP exhibits synergistic activation with nuclear receptor coactivators and functionally interacts in vivo with glucocorticoid receptor-interacting protein-1 and coactivator-associated arginine methyltransferase-1. We propose that SRCAP, by virtue of its ability to interact with CBP, functions as a coactivator to regulate transcription initiated by several signaling pathways.
Alexandra M Monroy - One of the best experts on this subject based on the ideXlab platform.
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the chromatin remodeling factor SRCAP modulates expression of prostate specific antigen and cellular proliferation in prostate cancer cells
Journal of Cellular Physiology, 2010Co-Authors: Artur Slupianek, Smitha Yerrum, Fayez F Safadi, Alexandra M MonroyAbstract:The SNF2-related CBP activator protein (SRCAP) serves as a coactivator for several nuclear receptors including the androgen receptor (AR). SRCAP is an ATPase that is the core subunit of a large multiprotein complex and was shown to incorporate the histone variant H2A.Z into nucleosomes. In this report, we demonstrate that SRCAP is expressed in the epithelium of normal prostate and in prostate carcinoma cells, and is associated with AR in the nucleus. Using transient transfection assays we demonstrate that SRCAP activates hormone-dependent transcription of the androgen responsive, prostate specific antigen (PSA)-Luciferase reporter gene in human prostate cells. The in vivo occupancy of SRCAP at the endogenous PSA promoter is demonstrated using chromatin immunoprecipitation assays. ShRNA mediated knockdown of SRCAP resulted in decreased H2A.Z binding at the enhancer region of the PSA promoter and decreased expression of PSA in prostate cancer cells. Furthermore, inhibition of SRCAP expression significantly inhibited androgen dependent prostate cancer cell growth. These data identify SRCAP as a physiologically relevant mediator of PSA expression, and demonstrate that SRCAP plays a role in prostate cancer cell proliferation.
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snf2 related cbp activator protein SRCAP functions as a coactivator of steroid receptor mediated transcription through synergistic interactions with carm 1 and grip 1
Molecular Endocrinology, 2003Co-Authors: Alexandra M Monroy, Natalie M Schott, Linda K Cox, Don J Chen, Mary F Ruh, John C ChriviaAbstract:SRCAP (SNF2-related CBP activator protein) is a 350-kDa protein that shares homology with the SNF2 family of proteins whose members function in various aspects of transcriptional regulation. In various cell types, SRCAP is found in distinct multiprotein complexes that include proteins found in SWI/SNF chromatin remodeling complexes. SRCAP was identified by its ability to bind to CBP and was found to potentiate the ability of CBP to activate transcription. Studies in our laboratory have demonstrated that SRCAP functions as a coactivator for CREB-mediated transcription of a number of promoters, including that of the phosphoenolpyruvate carboxykinase gene. Our current studies demonstrate that SRCAP enhances phosphoenolpyruvate carboxykinase promoter transcription induced by glucocorticoids. SRCAP also enhances glucocorticoid receptor-mediated transcription of a simple promoter containing only two glucocorticoid response elements, indicating that SRCAP functions as a glucocorticoid receptor coactivator. In similar studies, SRCAP was also found to serve as a coactivator for the androgen receptor. SRCAP exhibits synergistic activation with nuclear receptor coactivators and functionally interacts in vivo with glucocorticoid receptor-interacting protein-1 and coactivator-associated arginine methyltransferase-1. We propose that SRCAP, by virtue of its ability to interact with CBP, functions as a coactivator to regulate transcription initiated by several signaling pathways.
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molecular cloning and characterization of an SRCAP chromatin remodeling homologue in toxoplasma gondii
Parasitology Research, 2003Co-Authors: William J Sullivan, John C Chrivia, Alexandra M Monroy, Peter Yaciuk, Wolfgang Bohne, Karuna Nallani, Charles K Smith, Sherry F QueenerAbstract:We have identified and mapped a gene in Toxoplasma gondii that encodes a homologue of SRCAP (Snf2-related CBP activator protein), a member of the SNF/SWI family of chromatin remodeling factors. The genomic locus (TgSRCAP) is present as a single copy and contains 16 introns. The predicted cDNA contains an open reading frame of 8,775 bp and encodes a protein of 2,924 amino acids. We have identified additional SRCAP-like sequences in Apicomplexa for comparison by screening genomic databases. An analysis of SRCAP homologues between species reveals signature features that may be indicative of SRCAP members. Expression of mRNA encoding TgSRCAP is upregulated when tachyzoite (invasive form) parasites are induced to differentiate into bradyzoites (encysted form) in vitro. Recombinant TgSRCAP protein is functionally equivalent to the human homologue, being capable of increasing transcription mediated by CREB.
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regulation of camp responsive element binding protein mediated transcription by the snf2 swi related protein SRCAP
Journal of Biological Chemistry, 2001Co-Authors: Alexandra M Monroy, Peter Yaciuk, Donald D Ruhl, Daryl K Granner, John C ChriviaAbstract:Abstract SRCAP (SNF2-related CPB activator protein) belongs to the SNF2 family of proteins whose members participate in various aspects of transcriptional regulation, including chromatin remodeling. It was identified by its ability to bind to cAMP-responsive-binding protein (CREB)-binding protein (CBP), and it increases the transactivation function of CBP. The phosphoenolpyruvate carboxykinase (PEPCK) promoter was used as a model system to explore the role of SRCAP in the regulation of transcription mediated by factors that utilize CBP as a coactivator. We show that transcription of a PEPCK chloramphenicol acetyltransferase (CAT) reporter gene activated by protein kinase A (PKA) is enhanced 7-fold by SRCAP. In the absence of PKA this SRCAP-mediated enhancement does not occur, suggesting that SRCAP functions as a coactivator for PKA-activated factors such as CREB. Replacing the PEPCK promoter binding site for CREB with a binding site for Gal4 (ΔCRE (cAMP-responsive element) Gal4 PEPCK-CAT reporter gene) blocks the ability of SRCAP to activate transcription despite the presence of PKA. Expression of a Gal-CREB chimera restores the ability of PKA to regulate transcription of the ΔCRE Gal4 PEPCK gene and restored the ability of SRCAP to stimulate PKA-activated transcription. In addition, SRCAP in the presence of PKA enhances the ability of the Gal-CREB chimera to activate transcription of a Gal-CAT reporter gene that contains only binding sites for Gal4. SRCAP binds to CBP amino acids 280–460, a region that is important for CBP to function as a coactivator for CREB. Overexpression of a SRCAP peptide corresponding to this CBP binding domain acts as a dominant negative inhibitor of CREB-mediated transcription. Structure-function studies were done to explore the mechanism(s) by which SRCAP regulates transcription. These studies indicate that the N-terminal region of SRCAP, which contains five of the seven regions that comprise the ATPase domain, is not needed for activation of CREB-mediated transcription. SRCAP apparently has several domains that participate in the activation of transcription.
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adenovirus dna binding protein interacts with the snf2 related cbp activator protein SRCAP and inhibits SRCAP mediated transcription
Journal of Virology, 2001Co-Authors: Isaac Chackalaparampil, John C Chrivia, Alexandra M Monroy, Maria T Cannella, Elizabeth Pesek, Peter YaciukAbstract:The SNF2-related CBP activator protein, SRCAP (pronounced “sir cap”), shares homology with the SNF2/SWI2 protein family. SRCAP was cloned through its ability to bind CBP. SRCAP can function as a CBP coactivator and can activate transcription in a reporter assay when expressed as a Gal-SRCAP fusion protein. A monoclonal antibody raised against the carboxyl terminus of SRCAP coimmunoprecipitates CBP/p300, supporting the model that SRCAP is a CBP binding protein and that these proteins can be found together in a cellular protein complex. In addition, several cellular proteins are coimmunoprecipitated by the SRCAP-specific antibody. Since adenovirus E1A proteins interact with CBP/p300 proteins, we examined what proteins could be copurified in a SRCAP-specific coimmunoprecipitation assay from lysates of adenovirus-infected cells. While E1A proteins were not detected in this complex, to our surprise, we observed the presence of an infected-cell-specific band of 72 kDa, which we suspected might be the adenovirus DNA binding protein, DBP. The adenovirus DBP is a multifunctional protein involved in several aspects of the adenovirus life cycle, including an ability to modulate transcription. The identity of DBP was confirmed by DBP-specific Western blot analysis and by reimmunoprecipitating DBP from denatured SRCAP-specific protein complexes. Using in vitro-translated DBP and SRCAP proteins, we demonstrated that these proteins interact. To determine whether this interaction could affect SRCAP-mediated transcription, we tested whether increasing amounts of DBP could modulate the Gal-SRCAP transcription activity. We observed that DBP inhibited Gal-SRCAP transcription activity in a dose-dependent manner. These data suggest a novel mechanism of adenovirus host cell control by which DBP binds to and inactivates SRCAP, a member of the SNF2 chromatin-remodeling protein family.
Peter Yaciuk - One of the best experts on this subject based on the ideXlab platform.
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adenovirus dna binding protein inhibits SRCAP activated cbp and creb mediated transcription
Virology, 2003Co-Authors: Vera L Tarakanova, John C Chrivia, Peter YaciukAbstract:The SNF2-related CBP activator protein (SRCAP) is a potent activator of transcription mediated by CBP and CREB. We have previously demonstrated that the Adenovirus 2 DNA Binding Protein (DBP) binds to SRCAP and inhibits the transcription mediated by the carboxyl-terminal region of SRCAP (amino acids 1275-2971). We report here that DBP inhibits the ability of full-length SRCAP (1-2971) to activate transcription mediated by Gal-CREB and Gal-CBP. In addition, DBP also inhibits the ability of SRCAP to enhance Protein Kinase A (PKA) activated transcription of the enkaphalin promoter. DBP was found to dramatically inhibit transcription of a mammalian two-hybrid system that was dependent on the interaction of SRCAP and CBP binding domains. We also found that DBP has no effect on transcription mediated by a transcriptional activator that is not related to SRCAP, indicating that our reported transcriptional inhibition is specific for SRCAP and not due to nonspecific effects of DBP's DNA binding activity on the CAT reporter plasmid. Taken together, these results suggest a model in which DBP inhibits cellular transcription mediated by the interaction between SRCAP and CBP.
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molecular cloning and characterization of an SRCAP chromatin remodeling homologue in toxoplasma gondii
Parasitology Research, 2003Co-Authors: William J Sullivan, John C Chrivia, Alexandra M Monroy, Peter Yaciuk, Wolfgang Bohne, Karuna Nallani, Charles K Smith, Sherry F QueenerAbstract:We have identified and mapped a gene in Toxoplasma gondii that encodes a homologue of SRCAP (Snf2-related CBP activator protein), a member of the SNF/SWI family of chromatin remodeling factors. The genomic locus (TgSRCAP) is present as a single copy and contains 16 introns. The predicted cDNA contains an open reading frame of 8,775 bp and encodes a protein of 2,924 amino acids. We have identified additional SRCAP-like sequences in Apicomplexa for comparison by screening genomic databases. An analysis of SRCAP homologues between species reveals signature features that may be indicative of SRCAP members. Expression of mRNA encoding TgSRCAP is upregulated when tachyzoite (invasive form) parasites are induced to differentiate into bradyzoites (encysted form) in vitro. Recombinant TgSRCAP protein is functionally equivalent to the human homologue, being capable of increasing transcription mediated by CREB.
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regulation of camp responsive element binding protein mediated transcription by the snf2 swi related protein SRCAP
Journal of Biological Chemistry, 2001Co-Authors: Alexandra M Monroy, Peter Yaciuk, Donald D Ruhl, Daryl K Granner, John C ChriviaAbstract:Abstract SRCAP (SNF2-related CPB activator protein) belongs to the SNF2 family of proteins whose members participate in various aspects of transcriptional regulation, including chromatin remodeling. It was identified by its ability to bind to cAMP-responsive-binding protein (CREB)-binding protein (CBP), and it increases the transactivation function of CBP. The phosphoenolpyruvate carboxykinase (PEPCK) promoter was used as a model system to explore the role of SRCAP in the regulation of transcription mediated by factors that utilize CBP as a coactivator. We show that transcription of a PEPCK chloramphenicol acetyltransferase (CAT) reporter gene activated by protein kinase A (PKA) is enhanced 7-fold by SRCAP. In the absence of PKA this SRCAP-mediated enhancement does not occur, suggesting that SRCAP functions as a coactivator for PKA-activated factors such as CREB. Replacing the PEPCK promoter binding site for CREB with a binding site for Gal4 (ΔCRE (cAMP-responsive element) Gal4 PEPCK-CAT reporter gene) blocks the ability of SRCAP to activate transcription despite the presence of PKA. Expression of a Gal-CREB chimera restores the ability of PKA to regulate transcription of the ΔCRE Gal4 PEPCK gene and restored the ability of SRCAP to stimulate PKA-activated transcription. In addition, SRCAP in the presence of PKA enhances the ability of the Gal-CREB chimera to activate transcription of a Gal-CAT reporter gene that contains only binding sites for Gal4. SRCAP binds to CBP amino acids 280–460, a region that is important for CBP to function as a coactivator for CREB. Overexpression of a SRCAP peptide corresponding to this CBP binding domain acts as a dominant negative inhibitor of CREB-mediated transcription. Structure-function studies were done to explore the mechanism(s) by which SRCAP regulates transcription. These studies indicate that the N-terminal region of SRCAP, which contains five of the seven regions that comprise the ATPase domain, is not needed for activation of CREB-mediated transcription. SRCAP apparently has several domains that participate in the activation of transcription.
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adenovirus dna binding protein interacts with the snf2 related cbp activator protein SRCAP and inhibits SRCAP mediated transcription
Journal of Virology, 2001Co-Authors: Isaac Chackalaparampil, John C Chrivia, Alexandra M Monroy, Maria T Cannella, Elizabeth Pesek, Peter YaciukAbstract:The SNF2-related CBP activator protein, SRCAP (pronounced “sir cap”), shares homology with the SNF2/SWI2 protein family. SRCAP was cloned through its ability to bind CBP. SRCAP can function as a CBP coactivator and can activate transcription in a reporter assay when expressed as a Gal-SRCAP fusion protein. A monoclonal antibody raised against the carboxyl terminus of SRCAP coimmunoprecipitates CBP/p300, supporting the model that SRCAP is a CBP binding protein and that these proteins can be found together in a cellular protein complex. In addition, several cellular proteins are coimmunoprecipitated by the SRCAP-specific antibody. Since adenovirus E1A proteins interact with CBP/p300 proteins, we examined what proteins could be copurified in a SRCAP-specific coimmunoprecipitation assay from lysates of adenovirus-infected cells. While E1A proteins were not detected in this complex, to our surprise, we observed the presence of an infected-cell-specific band of 72 kDa, which we suspected might be the adenovirus DNA binding protein, DBP. The adenovirus DBP is a multifunctional protein involved in several aspects of the adenovirus life cycle, including an ability to modulate transcription. The identity of DBP was confirmed by DBP-specific Western blot analysis and by reimmunoprecipitating DBP from denatured SRCAP-specific protein complexes. Using in vitro-translated DBP and SRCAP proteins, we demonstrated that these proteins interact. To determine whether this interaction could affect SRCAP-mediated transcription, we tested whether increasing amounts of DBP could modulate the Gal-SRCAP transcription activity. We observed that DBP inhibited Gal-SRCAP transcription activity in a dose-dependent manner. These data suggest a novel mechanism of adenovirus host cell control by which DBP binds to and inactivates SRCAP, a member of the SNF2 chromatin-remodeling protein family.
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hepatitis c virus ns5a protein modulates transcription through a novel cellular transcription factor SRCAP
Journal of Biological Chemistry, 2000Co-Authors: Asish K Ghosh, John C Chrivia, Peter Yaciuk, Mainak Majumder, Robert Steele, Ranjit Ray, Ratna B RayAbstract:Hepatitis C virus NS5A protein transcriptionally modulates cellular genes and promotes cell growth. NS5A is likely to exert its activity in concert with cellular factor(s). Using a yeast two-hybrid screen, we have demonstrated that NS5A interacts with the C-terminal end of a newly identified cellular transcription factor, SRCAP. The authenticity of this interaction was verified by a mammalian two-hybrid assay, in vitro pull-down experiment, and anin vivo coimmunoprecipitation assay in human hepatoma (HepG2) cells. An in vitro transient transfection assay demonstrated that SRCAP can efficiently activate transcription when recruited by the Gal4 DNA-binding domain to the promoter. However, down-regulation of p21 promoter activity by NS5A was enhanced following ectopic expression of SRCAP. Together these results suggest that the interaction of NS5A and SRCAP may be one of the mechanisms by which NS5A exerts its effect on cell growth regulation contributing to hepatitis C virus-mediated pathogenesis.
Tadaaki Miyazaki - One of the best experts on this subject based on the ideXlab platform.
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Prevention of respiratory syncytial virus infection with probiotic lactic acid bacterium Lactobacillus gasseri SBT2055
Scientific Reports, 2019Co-Authors: Kei Eguchi, Naoki Fujitani, Hisako Nakagawa, Tadaaki MiyazakiAbstract:Lactobacillus gasseri SBT2055 (LG2055) is a probiotic lactic acid bacterium with multifunctional effects, including the prevention of influenza A virus infection in mice, reduction of adipocyte size in mice, and increased lifespan in C. elegans. We investigated whether LG2055 exhibits antiviral activity against respiratory syncytial virus (RSV), a global pathogen for which a preventive strategy is required. Following oral administration of LG2055 in mice, the RSV titre in the lung was significantly decreased, while body weight was not decreased after virus infection. Additionally, the elevated expression of pro-inflammatory cytokines in the lung upon RSV infection decreased after LG2055 administration. Moreover, interferon and interferon stimulated genes were upregulated by LG2055 treatment. Comparative cellular proteomic analysis revealed that SWI2/SNF2-related CREB-binding protein activator protein (SRCAP) was a candidate for the antiviral activity of LG2055 against RSV. There was a positive correlation between the inhibition of RSV replication and the suppression of SRCAP expression and RSV replication was suppressed by SRCAP silencing. Since SRCAP is a scaffold protein to which viral non-structural proteins bind, the downregulation of SRCAP induced by LG2055 could provide new insights about the inhibition of RSV replication. In summary, our study demonstrated that LG2055 has prophylactic potential against RSV infection.
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Hepatitis C Virus NS3 Protein Can Activate the Notch- Signaling Pathway through Binding to a Transcription
2016Co-Authors: Factor Srcap, Tsutomu Takegami, Atsushi Iwai, Takuya Shiozaki, Tadaaki MiyazakiAbstract:Persistent infections of hepatitis C virus (HCV) are known to be a major risk factor for causing hepatocellular carcinomas. Nonstructural protein 3 (NS3) of HCV has serine protease and RNA helicase domains, and is essential for the viral replication. Further, NS3 is also considered to be involved in the development of HCV-induced hepatocellular carcinomas. In this report, we focus on the function of NS3 protein, and propose a novel possible molecular mechanism which is thought to be related to the tumorigenesis caused by the persistent infection of HCV. We identified SRCAP (Snf2-related CBP activator protein) as a NS3 binding protein using yeast two-hybrid screening, and a co-immunoprecipitation assay demonstrated that NS3 can bind to SRCAP in mammalian cells. The results of a reporter gene assay using Hes-1 promoter which is known to be a target gene activated by Notch, indicate that NS3 and SRCAP cooperatively activate the Hes-1 promoter in Hep3B cells. In addition, we show in this report that also p400, which is known as a protein closely resembling SRCAP, would be targeted by NS3. NS3 exhibited binding activity also to the 1449–1808 region of p400 by a co-immunoprecipitation assay, and further the activation of the Notch-mediated transcription of Hes-1 promoter by NS3 decreased significantly by the combined silencing of SRCAP and p400 mRNA using short hairpin RNA. These results suggest that the HCV NS3 protein is involved in th
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hepatitis c virus ns3 protein can activate the notch signaling pathway through binding to a transcription factor SRCAP
PLOS ONE, 2011Co-Authors: Atsushi Iwai, Tsutomu Takegami, Takuya Shiozaki, Tadaaki MiyazakiAbstract:Persistent infections of hepatitis C virus (HCV) are known to be a major risk factor for causing hepatocellular carcinomas. Nonstructural protein 3 (NS3) of HCV has serine protease and RNA helicase domains, and is essential for the viral replication. Further, NS3 is also considered to be involved in the development of HCV-induced hepatocellular carcinomas. In this report, we focus on the function of NS3 protein, and propose a novel possible molecular mechanism which is thought to be related to the tumorigenesis caused by the persistent infection of HCV. We identified SRCAP (Snf2-related CBP activator protein) as a NS3 binding protein using yeast two-hybrid screening, and a co-immunoprecipitation assay demonstrated that NS3 can bind to SRCAP in mammalian cells. The results of a reporter gene assay using Hes-1 promoter which is known to be a target gene activated by Notch, indicate that NS3 and SRCAP cooperatively activate the Hes-1 promoter in Hep3B cells. In addition, we show in this report that also p400, which is known as a protein closely resembling SRCAP, would be targeted by NS3. NS3 exhibited binding activity also to the 1449–1808 region of p400 by a co-immunoprecipitation assay, and further the activation of the Notch-mediated transcription of Hes-1 promoter by NS3 decreased significantly by the combined silencing of SRCAP and p400 mRNA using short hairpin RNA. These results suggest that the HCV NS3 protein is involved in the activation of the Notch-signaling pathway through the targeting to both SRCAP and p400.
Ronald C Conaway - One of the best experts on this subject based on the ideXlab platform.
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purification and assay of the human ino80 and SRCAP chromatin remodeling complexes
Methods, 2006Co-Authors: Yong Cai, Ronald C Conaway, Jingji Jin, Aaron J Gottschalk, Tingting Yao, Joan W ConawayAbstract:Chromatin modifying and remodeling enzymes play critical roles in many aspects of chromosome biology including transcription, replication, recombination, and repair. Our laboratory recently identified and characterized two multisubunit human chromatin remodeling enzymes designated the INO80 and SRCAP complexes. Mechanistic studies revealed that the human INO80 complex catalyzes nucleosome sliding and the SRCAP complex catalyzes ATP-dependent exchange of histone H2A/H2B dimers containing the histone variant H2A.Z into nucleosomes. Here we describe methods for purification and assay of the INO80 and SRCAP chromatin remodeling complexes.
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purification of a human SRCAP complex that remodels chromatin by incorporating the histone variant h2a z into nucleosomes
Biochemistry, 2006Co-Authors: Donald D Ruhl, Selene K Swanson, Laurence Florens, Michael P Washburn, Ronald C Conaway, Joan Weliky Conaway, John C ChriviaAbstract:The Snf-2-related CREB-binding protein activator protein (SRCAP) serves as a coactivator for a number of transcription factors known to interact with CBP. Swr1, the closest Saccharomyces cerevisiae ortholog of SRCAP, is a component of the chromatin remodeling complex SWR-C, which catalyzes exchange of the histone variant H2A.Z into nucleosomes. In this report, we use a combination of conventional chromatography and anti-SRCAP immunoaffinity chromatography to purify a native human SRCAP complex with a polypeptide composition similar to that of SWR-C, and we show for the first time that this SRCAP-containing complex supports ATP-dependent exchange of histone dimers containing H2B and H2A.Z into mononucleosomes reconstituted with recombinant H2A, H2B, H3, and H4. Our findings, together with previous evidence implicating H2A.Z in transcriptional regulation, suggest that SRCAP's coactivator function may depend on its ability to promote incorporation of H2A.Z into chromatin.